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.\" copyright (C) 1997 Stephen Williams <steve@icarus.com>
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.TH MAJOR 9 "$Date:$" "Linux DDI" "Kernel Functions"
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.SH NAME
MAJOR, MINOR, MKDEV \- macros to manipulate device major/minor numbers
.\"
.\"
.SH SYNOPSIS
.B #include <linux/fs.h>
.sp
.BI "#define MAJOR(" dev ")"
.br
.BI "#define MINOR(" dev ")"
.br
.BI "#define MKDEV(" major ", " minor ")"
.HP
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.SH DESCRIPTION
The
.B MAJOR
and
.B MINOR
macros extract from a device id (of type
.IR dev_t )
the major and minor numbers respectively. It is the combined device
number that is found in the
.B "struct~file"
structure.
.PP
The
.B MKDEV
macro assembles a device number from the supplied major and minor
numbers.
.SH "RETURN VALUE"
Describe the return values. Enumerate all the distinct values and all
the ranges.
.SH AVAILABILITY
Linux 0.0+
.PP
In later kernels (Linux 2.1 and later) there is movement towards using
64bit device numbers. Although it is generally a good idea to not
presume to know how device numbers are constructed, it is during this
period of transition fundamentally important that you ONLY use these
functions to manipulate device numbers.
.SH "SEE ALSO"
.hlm 0
.na
.BR mknod "(1)"
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.hlm 1
.PP
Also list some source files for the
kernel that implement the functions of the page.
.SH AUTHOR
Stephen Williams <steve@icarus.com>
.SH BUGS
These are macros, so parameters may be evaluated multiple times.
